stat函数及ls功能

怼烎@ 2022-07-13 00:13 155阅读 0赞

stat filename

查看文件信息

![这里写图片描述][SouthEast]

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stat函数

#include <sys/types.h>
    #include <sys/stat.h>
    #include <unistd.h>
    
    int stat(const char *pathname, struct stat *buf);

ls -l filename 功能的实现：

#include <sys/types.h>
    #include <sys/stat.h>
    #include <unistd.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <pwd.h>
    #include <grp.h>
    #include <time.h>
    #include <string.h>
    
    int main(int argc, char* argv[])
    {
        if(argc < 2){
            printf("参数错误 argc < 2\n");
            exit(1);
        }
    
        struct stat st;
        int ret = stat(argv[1], &st);
        if(ret == -1){
            perror("stat");
            exit(1);
        }
    
        char perms[11]={
       0};
        //判断文件类型
        switch(st.st_mode & S_IFMT)
        {
            case S_IFLNK:
                perms[0] = 'l';
                break;
            case S_IFDIR:
                perms[0] = 'd';
                break;
            case S_IFREG:
                perms[0] = '-';
                break;
            case S_IFBLK:
                perms[0] = 'b';
                break;
            case S_IFCHR:
                perms[0] = 'c';
                break;
            case S_IFSOCK:
                perms[0] = 's';
                break;
            case S_IFIFO:
                perms[0] = 'P';
                break;
            default:
                perms[0] = '?';
                break;
        }
    
        //判断文件的访问权限
    
        //文件所有者
        perms[1] = (st.st_mode & S_IRUSR) ? 'r' : '-';
        perms[2] = (st.st_mode & S_IWUSR) ? 'w' : '-';
        perms[3] = (st.st_mode & S_IXUSR) ? 'x' : '-';
    
        //group
        perms[4] = (st.st_mode & S_IRGRP) ? 'r' : '-';
        perms[5] = (st.st_mode & S_IWGRP) ? 'w' : '-';
        perms[6] = (st.st_mode & S_IXGRP) ? 'x' : '-';
    
        //others
        perms[7] = (st.st_mode & S_IROTH) ? 'r' : '-';
        perms[8] = (st.st_mode & S_IWOTH) ? 'w' : '-';
        perms[9] = (st.st_mode & S_IXOTH) ? 'x' : '-';
    
        //硬链接计数
        int linkNum = st.st_nlink;
    
        //文件所有者
        char* fileUser = getpwuid(st.st_uid)->pw_name;
    
        //文件所属组
        char* fileGroup = getgrgid(st.st_gid)->gr_name;
    
        //文件大小
        int fileSize = (int)st.st_size;
    
        //修改时间
        char* time = ctime(&st.st_mtime);
        char mtime[512]={
       0};
        strncpy(mtime, time, strlen(time)-1);
        char buf[1024];
        sprintf(buf, "%s %d %s %s %d %s %s",perms, linkNum, fileUser, fileGroup, fileSize, mtime, argv[1]);
        printf("%s\n", buf);
    
        return 0;
    }

![这里写图片描述][SouthEast 1]

[SouthEast]: /images/20220713/e739843aff384a7c8a116fbfabb05713.png
[SouthEast 1]: /images/20220713/6154fcfc561240f4bbda10bc939462a8.png